The intense rainstorms sweeping in from the Pacific Ocean began to pound central California on Christmas Eve in 1861 and continued virtually unabated for 43 days. The deluges quickly transformed rivers running down from the Sierra Nevada mountains along the state’s eastern border into raging torrents that swept away entire communities and mining settlements. The rivers and rains poured into the state’s vast Central Valley, turning it into an inland sea 300 miles long and 20 miles wide. Thousands of people died, and one quarter of the state’s estimated 800,000 cattle drowned. Downtown Sacramento was submerged under 10 feet of brown water filled with debris from countless mudslides on the region’s steep slopes. California’s legislature, unable to function, moved to San Francisco until Sacramento dried out—six months later. By then, the state was bankrupt.

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Atmospheric rivers are long streams of water vapor that form at about one mile up in the atmosphere. They are only 250 miles across but extend for thousands of miles—sometimes across an entire ocean basin such as the Pacific. These conveyor belts of vapor carry as much water as 10 to 15 Mississippi Rivers from the tropics and across the middle latitudes. When one reaches the U.S. West Coast and hits inland mountain ranges, such as the Sierra Nevada, it is forced up, cools off and condenses into vast quantities of precipitation.

People on the West Coast of North America have long known about storms called “pineapple expresses,” which pour in from the tropics near Hawaii and dump heavy rain and snow for three to five days. It turns out that they are just one configuration of an atmospheric river. As many as nine atmospheric rivers hit California every year, according to recent investigations. Few of them end up being strong enough to yield true megafloods, but even the “normal” storms are about as intense as rainstorms get in the rest of the U.S., so they challenge emergency personnel as well as flood-control authorities and water managers.

Atmospheric rivers also bring rains to the west coasts of other continents and can occasionally form in unlikely places. For example, the catastrophic flooding in and around Nashville in May 2010—which caused some 30 deaths and more than $2 billion in damages—was fed by an unusual atmospheric river that brought heavy rain for two relentless days up into Tennessee from the Gulf of Mexico. In 2009 substantial flooding in southern England and in various parts of Spain was also caused by atmospheric rivers. But the phenomenon is best understood along the Pacific Coast, and the latest studies suggest that these rivers of vapor may become even larger in the future as the climate warms.

Climate change looks likely to increase their frequency *and* intensity. Imagine a bell curve distribution for the frequency of pineapple expresses at different severities. Now move the curve a little to the right along the x-axis (severity). Also raise it up a little along the y-axis to increase the area under the graph (frequency). It should be obvious that small changes such as these can quickly lead to the extreme outliers occurring much more frequently. Maybe a devastating, once in 200 years flood could increase to once every few decades. That's bad news for California.

Quote:

To provide an example that California emergency managers could use to test their current plans and methods, scientists at the U.S. Geological Survey recently developed the scenario mentioned at the start of this article: a megastorm that rivaled the 1861–62 storm in size but lasted 23 days instead of 43 (so no one could claim that the scenario was unrealistic). To further ensure that the scenario, which was eventually dubbed ARkStorm (Atmospheric River 1000 Storm), was as realistic as possible, scientists constructed it by stitching together data from two of the largest storm sequences in California from the past 50 years: January 1969 and February 1986.

When project leaders ran the events of ARkStorm through a variety of weather, runoff, engineering and economic models, the results suggested that sustained flooding could occur over most lowland areas of northern and southern California. Such flooding could lead to the evacuation of 1.5 million people. Damages and disruptions from high water, hundreds of landslides and hurricane-force winds in certain spots could cause $400 billion in property damages and agricultural losses. Long-term business and employment interruptions could bring the eventual total costs to more than $700 billion. Based on disasters elsewhere in recent years, we believe a calamity this extensive could kill thousands of people (the ARkStorm simulation did not predict deaths).

The costs are about three times those estimated by many of the same USGS project members who had worked on another disaster scenario known as ShakeOut: a hypothetical magnitude 7.8 earthquake in southern California. It appears that an atmospheric-river megastorm—California’s “Other Big One”—may pose even greater risks to the Golden State than a large-magnitude earthquake. An ARkStorm event is plausible for California, perhaps even inevitable. And the state’s flood protection systems are not designed to handle it.

The same kind of thing is true across the board for all kinds of weather events. Maybe a once in 50 year heatwave which causes crop failures might start to occur every few years, or a one in a hundred years wildfire might become once every couple of decades. A lot of the details aren't known for certain but we do know that pumping vast amounts of extra energy into the earth's climate systems will inevitably create big changes in weather patterns and huge dollar damages from failed crops and destroyed property.

Climate change looks likely to increase their frequency *and* intensity. Imagine a bell curve distribution for the frequency of pineapple expresses at different severities. Now move the curve a little to the right along the x-axis (severity). Also raise it up a little along the y-axis to increase the area under the graph (frequency). It should be obvious that small changes such as these can quickly lead to the extreme outliers occurring much more frequently. Maybe a devastating, once in 200 years flood could increase to once every few decades. That's bad news for California.

Quote:

To provide an example that California emergency managers could use to test their current plans and methods, scientists at the U.S. Geological Survey recently developed the scenario mentioned at the start of this article: a megastorm that rivaled the 1861–62 storm in size but lasted 23 days instead of 43 (so no one could claim that the scenario was unrealistic). To further ensure that the scenario, which was eventually dubbed ARkStorm (Atmospheric River 1000 Storm), was as realistic as possible, scientists constructed it by stitching together data from two of the largest storm sequences in California from the past 50 years: January 1969 and February 1986.

When project leaders ran the events of ARkStorm through a variety of weather, runoff, engineering and economic models, the results suggested that sustained flooding could occur over most lowland areas of northern and southern California. Such flooding could lead to the evacuation of 1.5 million people. Damages and disruptions from high water, hundreds of landslides and hurricane-force winds in certain spots could cause $400 billion in property damages and agricultural losses. Long-term business and employment interruptions could bring the eventual total costs to more than $700 billion. Based on disasters elsewhere in recent years, we believe a calamity this extensive could kill thousands of people (the ARkStorm simulation did not predict deaths).

The costs are about three times those estimated by many of the same USGS project members who had worked on another disaster scenario known as ShakeOut: a hypothetical magnitude 7.8 earthquake in southern California. It appears that an atmospheric-river megastorm—California’s “Other Big One”—may pose even greater risks to the Golden State than a large-magnitude earthquake. An ARkStorm event is plausible for California, perhaps even inevitable. And the state’s flood protection systems are not designed to handle it.

The same kind of thing is true across the board for all kinds of weather events. Maybe a once in 50 year heatwave which causes crop failures might start to occur every few years, or a one in a hundred years wildfire might become once every couple of decades. A lot of the details aren't known for certain but we do know that pumping vast amounts of extra energy into the earth's climate systems will inevitably create big changes in weather patterns and huge dollar damages from failed crops and destroyed property.

Climate change looks likely to increase their frequency *and* intensity. Imagine a bell curve distribution for the frequency of pineapple expresses at different severities. Now move the curve a little to the right along the x-axis (severity). Also raise it up a little along the y-axis to increase the area under the graph (frequency). It should be obvious that small changes such as these can quickly lead to the extreme outliers occurring much more frequently. Maybe a devastating, once in 200 years flood could increase to once every few decades. That's bad news for California.

Quote:

To provide an example that California emergency managers could use to test their current plans and methods, scientists at the U.S. Geological Survey recently developed the scenario mentioned at the start of this article: a megastorm that rivaled the 1861–62 storm in size but lasted 23 days instead of 43 (so no one could claim that the scenario was unrealistic). To further ensure that the scenario, which was eventually dubbed ARkStorm (Atmospheric River 1000 Storm), was as realistic as possible, scientists constructed it by stitching together data from two of the largest storm sequences in California from the past 50 years: January 1969 and February 1986.

When project leaders ran the events of ARkStorm through a variety of weather, runoff, engineering and economic models, the results suggested that sustained flooding could occur over most lowland areas of northern and southern California. Such flooding could lead to the evacuation of 1.5 million people. Damages and disruptions from high water, hundreds of landslides and hurricane-force winds in certain spots could cause $400 billion in property damages and agricultural losses. Long-term business and employment interruptions could bring the eventual total costs to more than $700 billion. Based on disasters elsewhere in recent years, we believe a calamity this extensive could kill thousands of people (the ARkStorm simulation did not predict deaths).

The costs are about three times those estimated by many of the same USGS project members who had worked on another disaster scenario known as ShakeOut: a hypothetical magnitude 7.8 earthquake in southern California. It appears that an atmospheric-river megastorm—California’s “Other Big One”—may pose even greater risks to the Golden State than a large-magnitude earthquake. An ARkStorm event is plausible for California, perhaps even inevitable. And the state’s flood protection systems are not designed to handle it.

The same kind of thing is true across the board for all kinds of weather events. Maybe a once in 50 year heatwave which causes crop failures might start to occur every few years, or a one in a hundred years wildfire might become once every couple of decades. A lot of the details aren't known for certain but we do know that pumping vast amounts of extra energy into the earth's climate systems will inevitably create big changes in weather patterns and huge dollar damages from failed crops and destroyed property.

Don't worry. Pineapple Expresses rarely impact Southern California. The Bay area is about the southern norm. All the commies in Hollywood are safe._________________The further a society drifts from truth, the more it will hate those who speak it.
George Orwell